Many websites allow users to conduct a variety of actions online, such as view content, write reviews, order items, purchase tickets, etc. These websites often present the user with a plurality of actions to choose from and allow the user to select the type of action he would like to perform. Once the action is selected, the website typically redirects the client system of the user to a webpage where the action can be completed. For example, some websites allow users to organize events using an online event management system. An online event management system may allow an event organizer to organize and manage various aspects of an event, such as, for example, managing attendee registrations and selling tickets, promoting the event, and managing attendee check-in at the event. An online event management system may also allow users to view event listings, register for events, and purchase tickets for events. Online systems, such as online event management systems, can typically be accessed using suitable browser clients (e.g., Firefox, Chrome, Internet Explorer).
Some users of an online event management system may attempt to improperly use the system, such as by violating the terms of services of the system or by using the system to commit illegal acts. One type of improper use is creating event listings that contain spam or other improper advertisements. For example, a user may create an online event listing for a fake event and then use the event listing to display an advertisement for a product (e.g., erectile dysfunction drugs, nutraceuticals, pornography). Another type of improper use is creating event listings in order to make fraudulent financial transactions. For example, a user may create an online event listing for a fake event. The user, and possibly one or more accomplices, may then use stolen credit cards to purchase tickets to the fake event. The user may then request that the system pay out money to the user for the fraudulently purchased tickets. If the online event management system pays out the money before the purchases can be verified (such as, for example, by a credit card processor, a credit card issuer, or a fraud detection system) the system may lose money when the fraudulent purchases are declined by the credit card processor.